Cloudlet based network provides a platform to offloading the traffic workload generated by mobile devices. It can significantly reduce the access delay for mobile application users. However, the high dynamic mobility of users brings significant challenges to the service provisioning for mobile applications, especially for the delay-sensitive big data applications. To increase the overall admitted traffic served by local cloudlets, and to reduce the access delay as well as the virtual-machine migration delay, this paper aims to study the adaptively service-provisioning update scheme for a given group of mobile users under a cloudlet-based network. A profit maximization problem is first formulated as an integer linear programming using absolute value manipulation techniques. Then, we propose a framework of heuristic algorithms to solve this problem. The numerical simulation results demonstrate the efficiency of the proposed algorithms.